Summary:An intelligent substation monitoring system has been designed to address the current issues with the substation monitoring system, such as incomplete functions, difficulty in interaction, and the need for manual intervention in basic maintenance. The system consists of terminal control units, transmission networks, and a remote monitoring center. The terminal control units are responsible for environmental parameter monitoring, instrument reading, central command receiving and decoding, and data upload. Each substation is connected to the remote monitoring center via VPN. The remote monitoring center handles real-time data processing, database storage, and system front-end interface services. After testing, the system has achieved the expected effects, including temperature and humidity monitoring, smoke alarms, wind-cooled heat dissipation control, lighting control, water supply and drainage control, and electromechanical instrument monitoring. It effectively improves the operation and maintenance management of intelligent substations, ensuring safe, stable, and efficient operation, and achieving unattended operation.
Keywords:Substation; Intelligent Monitoring System; Instrument Reading; VPN; Unattended Operation
0 Introduction
Substations are a crucial component of the power generation, transmission, and distribution systems, primarily responsible for executing power distribution tasks within their respective regions. They are essential for ensuring the stable operation of the power grid. Often located in remote areas and dispersed, with the expansion of China's power grid and the increasing number of substations, manual monitoring is no longer sufficient to meet the operational and maintenance management needs. Therefore, the use of data collection and monitoring systems for remote control is vital. While many substations have already implemented monitoring of core equipment such as transformers and circuit breakers, there is a significant lack of monitoring for environmental parameters like temperature and humidity, lighting, as well as for various electromechanical equipment indicators. Moreover, basic operation and maintenance still require manual intervention. Additionally, the existing monitoring systems within substations are relatively independent, leading to issues such as difficulties in function reuse and server resource waste.
To address the aforementioned issues, the article proposes an intelligent substation monitoring system that can provide real-time monitoring of the substation's operating environment and the data from various equipment indicators, effectively enhancing the operation and maintenance management of smart substations, ensuring their safe, stable, and efficient operation, and achieving unattended operation.
System Overview
The system consists of three main parts: the Terminal Control Unit, the Transmission Network, and the Remote Monitoring Center. The Terminal Control Unit integrates various auxiliary terminal devices such as sensors and actuator equipment, enabling functions like environmental parameter monitoring, instrument reading, central command receiving and parsing, and data upload. Each substation, as an individual station, is connected to the remote monitoring center via VPN to ensure the system operates within a virtual local area network, effectively preventing external intrusions. The Remote Monitoring Center is capable of real-time data processing, database storage, and system frontend interface services. The overall system architecture is shown in Figure 1.
2 Hardware Design
2.1 Terminal Control Unit
The Terminal Control Unit consists of three main parts: the Master Control Module, the Command Module, and the Communication Module. The Master Control Module is the core of the Terminal Control Unit, responsible for processing various parameter data information from terminal devices, such as environment and instruments, into system-recognizable physical values and transmitting them to the remote monitoring center. It also feeds back alarm information from the monitoring center to all equipment and execution units, thereby realizing data interaction. The Command Module is responsible for parsing control instructions from the Master Control Module and sending the command programs to various electrical equipment. The Communication Module, which is the basic communication configuration of the system's lower parts.
The terminal control unit is powered by an S3C6410 chip as the processor core, with a high frequency of up to 667Hz and support for up to 512M memory. The sensor chosen is the FT-WQX7 seven-parameter integrated environmental monitoring sensor, which offers high integration of meteorological standard parameters. It can continuously and in real-time monitor environmental elements such as temperature, relative humidity, atmospheric pressure, wind direction, wind speed, light intensity, and rainfall, with high measurement accuracy and stable performance. Moreover, the instrument monitoring relies on substation patrol robots, where the robots carry cameras to capture images of the instruments to be identified. The remote monitoring center can then obtain the operational status of all equipment in the substation through real-time data analysis.
2.2 Transmission Network
The intelligent monitoring system for substation nodes requires multiple intercommunications, such as sensor nodes with terminal control units, and terminal control units with remote monitoring centers. Therefore, the system design employs various communication methods.
2.2.1 Sensor Nodes and Terminal Control Units
To minimize wiring and reduce the complexity of system deployment, the communication between the sensor nodes and terminal control units of this system is based on ZigBee. ZigBee, adhering to the IEEE 802.15.4 standard, can simultaneously network up to 254 nodes, offering high reliability to meet the requirements of the substation intelligent monitoring system.
2.2.2 Instrumentation Monitoring System and Terminal Control Unit
The current substation patrol robots primarily transmit data through WIFI wireless bridges, but this communication method has a low level of network security. Therefore, the system has been upgraded with an encrypted communication module, utilizing a wireless private network module that supports the WAPI wireless standard. This enables smooth communication between the instrument monitoring system and the terminal control unit, effectively preventing external intrusions.
2.2.3 Terminal Control Unit and Remote Monitoring Center
The Terminal Control Unit and Remote Monitoring Center communicate via TCP/IP protocol. Due to the large volume of data received, considering the real-time and stable transmission of data and commands, the system employs Ethernet communication to facilitate information exchange between the Terminal Control Unit and the Remote Monitoring Center.
Due to the two interface types for the Ethernet interface, namely the standard R45 interface and the SPF fiber optic interface, and considering the system's need for long-distance transmission and the strong electromagnetic interference present in substation environments, the use of fiber optic communication cables for transmission can greatly mitigate the impact of electromagnetic interference, ensuring stable signal transmission.
2.2.4 Other Communications
Due to the need for the system to add corresponding monitoring terminals and sensors based on the actual scene requirements of the substation, different bus and communication interfaces are reserved in the design to ensure high compatibility and expandability, such as CAN bus interfaces, RJ45 interfaces, RS232 interfaces, and so on.
3 System Testing
The intelligent monitoring system has been successfully applied on-site at the substation, with the system performing well according to actual field tests.
3.1 Pointer Instrument Recognition Test
A total of 100 instrument images were selected for the numerical recognition test. Table 1 shows a comparison of some experimental results. The visual results versus the system's recognition results indicate that the system's recognition accuracy can reach 98%. The instrument pointer recognition performance is excellent, providing strong technical support for the electromechanical instrument monitoring subsystem.
3.2 System Overall Testing
Field test results indicate that the system's various devices have performed well, with a high success rate. This has achieved real-time monitoring of the substation's operating environment and the pointers of various equipment instruments, ensuring its safe, stable, and effective operation.
Ankorri Power Monitoring Solution
5.1 Overview
For user substation (generally 35kV and below), a comprehensive automated monitoring system is achieved through the integration of devices such as microcomputer protection units, integrated control and measurement devices for switch cabinets, wireless temperature measurement products for electrical junctions, online power quality monitoring devices, distribution room environmental monitoring equipment, and arc protection devices. This system ensures the safe operation and comprehensive management of substation, distribution, and power consumption. The monitoring scope includes user substation, switch stations, transformer stations, and distribution rooms.
The Acrel-2000Z Power Monitoring System is a hierarchical distributed substation monitoring and management system developed by Ankorui Electric Co., Ltd. in response to the requirements for power system automation and unattended operation. It is designed for voltage levels of 35kV and below. This system integrates protection, monitoring, control, and communication functions into an open, networked, modular, and configurable system, utilizing power automation technology, computer technology, network technology, and information transmission technology. It is suitable for urban, rural, and user substation transformer stations with voltage levels of 35kV and below. The system enables control and management of substation operations, fulfilling the needs for unattended or minimally attended substation operations, and provides a solid guarantee for the safe, stable, and economic operation of substation transformers.
5.2 Application Sites
Design, construction, and operation and maintenance services for 35kV and below power distribution automation systems at the user end for rail transit, industry, construction, schools, commercial complexes, and more.
5.3 System Architecture
The Acrel-2000Z Power Monitoring System employs a hierarchical distributed design, which can be divided into three layers: the station control management layer, the network communication layer, and the field equipment layer. The networking methods can be a standard network structure, an optical fiber star network structure, or an optical fiber ring network structure. The networking method is determined by considering various factors such as the scale of electricity consumption, distribution of electrical equipment, and land area.
5.4 System Function
(1) Real-time Monitoring: Provides a direct display of the operation status of the distribution network, real-time monitoring of electrical parameters in each loop, and dynamic surveillance of fault and alarm signals related to distribution loops.
(2) Electrical Parameter Inquiry: Detailed electrical parameters of the circuit can be directly viewed on the primary distribution diagram.
(3) Curve Query: Directly view curves of various electrical parameters.
(4) Operational Reports: Query operational parameters for each circuit or equipment's runtime.
(5) Real-time Alerts: The system features real-time alerting capabilities, enabling it to detect changes in remote signaling for distribution circuit protection actions and fault tripping, among other events.
(6) Historical Event Inquiry: Stores and manages event records to facilitate users in tracing historical system events and alarms, as well as for query statistics and accident analysis.
(7) Electric Power Statistics Report: The system features a scheduled meter reading and summary function, allowing users to freely inquire about the power usage of each distribution node within any time period since the system's normal operation.
(8) User Access Management: The feature for user access management has been set up, enabling the definition of login names, passwords, and operational permissions for users at different levels.
(9) Network Topology: Supports real-time monitoring and diagnosis of communication status for all devices, providing a complete display of the entire system's network structure.
(10) Power Quality Monitoring: Continuous monitoring of power quality and reliability across the entire distribution system range is available.
(11) Remote Control Function: Allows for remote operation of equipment within the entire distribution system range.
(12) Fault Recording: Automatically and accurately records changes in various electrical quantities before and after a system fault occurs.
(Memorial of Incident: Automatically records all real-time stable information around the time of an incident.)
(14) Web Access: The display page shows an overview of substation quantities, transformer quantities, monitoring point quantities, and other general information, equipment communication status, electricity usage analysis, and event records.
(15) APP Access: The Device Data page displays the electrical parameter data and curves for each device.
5 Closing Remarks
This article proposes an intelligent substation monitoring system that achieves real-time monitoring of the operational environment and various equipment pointer instruments in the substation, effectively improving the operation and maintenance management of intelligent substations. It ensures their safe and stable operation, effectively addressing the current issues of incomplete substation monitoring systems, such as the difficulty in function reuse, interaction, and the reliance on manual intervention for basic operation and maintenance, thereby achieving unattended operation.
References
Song Menghua, Wang Ze, Jiang Qianji, Sun Huifang, Design and Implementation of an Intelligent Substation Monitoring System
Hu Bin, Sun Zhen, Tie Yongkui, et al. Intelligent Monitoring System for Substation Auxiliary Equipment[J]. Electrician Technology, 2021(07): 110-113.
Jiang Shuanlei, Cheng Weiming, Chen Kai, et al. Research on Online Real-Time Motor Temperature Monitoring System Based on LoRa and ARM [J]. Agricultural Equipment and Vehicle Engineering, 2021, 59(03): 93-97
Ankorri Enterprise Microgrid Application Manual. 2022.05 Edition.
